Edge Pro + DMT XC + Gerber = FAIL

Thu Feb 21, 2013 8:29 pm

In my intro post I described how my experience with sending my kitchen knives to a 'professional sharpener' got me back into the sharpening fold. Well... and this is difficult to say in this forum... They were Gerber Balance Plus. [Go ahead. Laugh. Get it all out of your system. There. Feel better?]

These knives have been all I've used since the mid 80s. Sure, they're heavy and far from laser-like, but when tuned up they've done a good job for me. The 10" chef's with aluminum handle fits my hand and is like an extension of my arm. And since you can find dull but like new pre-Fiskar Gerbers on eBay for chump change, my Edge Pro has a long career ahead of it.

My current problem lies with a cleaver. The sharpening service took it to a belt and tried to give me a convex edge. Which was more like a patchwork of random angled edges with no rhyme or reason. I really should have taken a picture of it for posterity. I figured I would match the most acute angle from the belt and use this cleaver as a heavy slicer or veggie chopper, since I have an identical cleaver with a stout angle for Western cleaver duty.

So I mount my DMT XC and giddyap. Lucky I had a 3 day weekend. After about 6 hours of working in sections I'm maybe 3/4 of the way to a reprofile. I even tried a freshly lapped EP 120 stone just for fun and the knife absolutely shrugged it off. (Actually, at this point my fun meter was bouncing off the lower stop.)

I have used this DMT plate on 3 knives previously. Never applied any pressure, only allowing the (relatively substantial) weight of the plate to do the work. Always used wet. I DO work it on both leading and trailing strokes. I'm seeing swarf floating up and being washed away, but the progress is painful. Do you think I may have worn it down so soon (unlikely) or pulled the diamonds out with leading strokes as Ben Dale warns?

Finding accurate info on the steel Gerber used in the Balance Plus line is difficult. I'm pretty sure this stuff isn't the M2 high speed tool steel, but rather 440A with some attention paid to HT. Dying to know more.

Not having the common sense to call it quits, I have an Atoma 140 on the way from Mark. I'm hoping this weekend will be more fruitful than the last. Given the rather disappointing performance from the DMT should I restrict myself to trailing edge strokes until the diamonds have worn down some? I don't want to jack up another stone if indeed that is the problem with the DMT.

Re: Edge Pro + DMT XC + Gerber = FAIL

The Atoma 140 EP should be considerably more aggressive than the XC DMT. Use it with water and also coat the edge with a sharpie marker to see that you are getting to the 'edge of the edge'.

Don't restrict to edge trailing only. Don't lean on it letting the plate do the work with modest pressure. Use it wet. The initial use will be the plate at it's roughest - this sounds like a good one to break the plate in. Then it will settle down as all diamond plates do. Diamond plates last longer used wet. Let us know how it works out.

Re: Edge Pro + DMT XC + Gerber = FAIL

Sat Feb 23, 2013 2:57 pm

Thanks for the reply Ken! I was hesitant to just start plowing leading strokes with a new Atoma lest my sharpening station fill with diamond particles. I might *still* break it in with trailing passes for the first few dozen or so strokes.

And, yes, even though the DMT website claims wet or dry, I always use water if for no other reason than to float off the steel particles.

Re: Edge Pro + DMT XC + Gerber = FAIL

Wed Feb 27, 2013 8:16 pm

I received the Atoma 140 from Mark. With the diamonds arranged in a neat matrix it is a thing of beauty! My fiancee said I should put it on a chain around my neck and wear it as bling. She also shoots two finger pistols at me and says, "Stay sharp!" whenever she walks by me at my sharpening kit. I can't help but think she's mocking me.

The Atoma 140 is much more aggressive than the DMT XC, however it is no panacea. It cuts steel faster than the DMT, but I still can't use terms like 'hot knife through butter' or similar hyperbole. Just noticably faster. Although the scratch pattern is obviously deeper than the DMT, it also seems more even due to the diamond matrix of the Atoma as opposed to the random diamonds in the DMT. Nice! I think the DMT might be relegated to stone flattening duty.

This steel is just plain abrasion resistant. A Gerber consumer services supervisor told me that it was 420HC, which is not known for hardness (Rc 59 max) or edge holding. Maybe Gerber hit on the worst of all worlds and made a blade which is the devil to sharpen and can't hold an edge? And yet, some of the older knives I pulled off of eBay suffer from edge chipping, which I would surmise would be partly due to steel hardness. (?) Or a bad temper? I know that after moderate home use these knives fold over a bit, but a few light swipes across my F. Dick smooth oval brings the edge right back. I would love to get to the bottom of this steel. Makes me wish I had paid more attention in metallurgy class.